1. Field of the Invention
The present invention relates to a stereo image display system that performs imaging (image capturing) of an object from viewpoints different from each other to produce and display parallax images having a parallax therebetween.
2. Description of the Related Art
A stereo image display system is conventionally proposed which displays right and left parallax images in a time-sharing manner and introduces light fluxes from the right and left parallax images to observer's right and left eyes in synchronization with timing of the time-shared display to enable observation of a stereo image. Moreover, a stereo image display system is also conventionally proposed which simultaneously displays right and left parallax images by using two polarized lights whose polarizing axes are orthogonal to each other and introduces these polarized lights to observer's right and left eyes through right and left polarizing filters whose polarizing axes are orthogonal to each other to enable observation of a stereo image.
Each of these stereo image display systems has a parallax condition corresponding to a fusional limit over which observers cannot recognize the right and left parallax images as a stereo image but as a double image due to a display principle and human's visual characteristics. The display of the double image due to a parallax exceeding the fusional limit provides a strong feeling of strangeness, fatigue or discomfort to the observers.
Furthermore, a stereo imaging apparatus is conventionally proposed which performs imaging of an object from right and left viewpoints different from each other to produce right and left parallax images having a parallax therebetween. This imaging apparatus assumes a size of a display screen on which the parallax images are displayed and an observing distance (viewing distance) that is a distance from the display screen to an observer, and controls a base length between the right and left viewpoints and a convergence angle from the right and left viewpoints such that the parallax does not exceed the fusional limit.
In addition, Japanese Patent Laid-Open No. 07-167633 discloses a stereo imaging apparatus integrated with a display apparatus. This stereo imaging apparatus calculates a parallax amount between parallax images produced by itself, and calculates a depth position where the stereo image is presented, on the basis of the parallax amount and a display condition of a display apparatus that displays the parallax images. Then, this stereo imaging apparatus adjusts, according to the depth position, a base length and a convergence angle thereof such that the parallax does not exceed the fusional limit of the observer.
However, the fusional limit is significantly changed depending on the size of the display screen and the viewing distance of the display apparatus. Therefore, even though the base length and the convergence angle are controlled according to the assumed display condition as disclosed in Japanese Patent Laid-Open No. 07-167633, a base length or a convergence angle greatly different from that of the assumed display condition causes the parallax to exceed the fusional limit.
Moreover, it is easy to adjust the base length and the convergence angle such that the parallax does not exceed the fusional limit since the stereo imaging apparatus disclosed in Japanese Patent Laid-Open No. 07-167633 is integrated with the display apparatus. However, when displaying the parallax images produced by this stereo imaging apparatus on an external (different) display apparatus, it is difficult to control the base length and the convergence angle such that the parallax does not exceed the fusional limit.